Nanopatterning is an essential part of nanotechnology research for fabricating nanostructures. For these nanostructures and nanopatterning techniques to have significant practical value, low cost and high throughput nanopatterning techniques are indispensable. Among many new emerging techniques that are aimed at lowering cost and increasing throughput, nanoimprint lithography (NIL) is regarded as a promising technique. NIL has the capability of patterning sub-10 nm structures, yet only entail simple equipment setup and easy processing. As such, NIL has been applied in the fabrication of numerous electric and optical devices, and also in wafer-scale processing.
There are, however, obstacles that prevent NIL from being an onmnipotent solution for the requirements associated with the next generation lithography of nanostructures. Convention NIL requires high temperature and high pressure during imprinting, and such conditions are especially unsuitable for microelectronics fabrication. Step-and-Flash Imprint Lithography (S-FIL) is another technique based on mechanical imprinting but uses a UV curable liquid material as a liquid resist. With S-FIL, the liquid resist is dispensed in droplet form onto a substrate, and then a template is brought into contact with the substrate and pressed against the substrate to spread out the liquid resist thereby forming a film of the liquid resist. This film is then cured by exposure to UV light. S-FIL can be carried out at room temperature and, therefore, does not require high temperatures like conventional NIL. However, S-FIL is still not ideal because the thickness and uniformity of the resist and resultant residual layer are difficult to control because the film of the liquid resist is formed by spreading under pressure. Spreading under pressure can be inconsistent. In addition, the UV curable liquid materials used in S-FIL are typically based on a mechanism involving free radical polymerization of acrylic functional monomers and oligomers. This mechanism typically exhibits extensive shrinkage after cure and is also prone to oxygen sensitivity where oxygen scavenges free radical species thereby inhibiting polymerization at a surface of the resist which makes S-FIL prone to defect generation in the resultant nanostructure. Finally, to achieve low viscosity for low pressure imprinting, reactive monomers are usually needed and the conventional material compositions of the prior art typically rely on reactive monomers that have low molecular weights (e.g. <300 Daltons) and are, therefore, volatile and emit unpleasant odors.
Thus, there remains a need for a material composition that improves upon the conventional material compositions typically relied on in the conventional NIL and in S-FIL techniques and that can be used in nano- and micro-lithography using conventional tools and equipment at low temperature and low pressure.